Waste Heat Recovery

[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]

December 08, 2014

Researchers at Penn State University have demonstrated the efficient conversion of low-grade thermal energy into electrical power using a thermally regenerative ammonia-based battery (TRAB). A paper on their work is published in the RSC journal Energy & Environmental Science.

The battery uses copper-based redox couples [Cu(NH3)42+/Cu and Cu(II)/Cu]. Ammonia addition to the anolyte (the electrolyte surrounding the anode) of a single TRAB cell produced a maximum power density of 115 ± 1 W m−2 (based on projected area of a single copper mesh electrode), with an energy density of 453 Wh m−3 (normalized to the total electrolyte volume, under maximum power production conditions).

December 03, 2014

GMZ Energy, a market leader in the development of high-temperature thermoelectric generation (TEG) solutions, has successfully demonstrated a 1,000W TEG designed for diesel engine exhaust heat recapture in a Bradley Fighting Vehicle. (Earlier post.) This announcement follows GMZ’s June 2014 demonstration of its 200W diesel TEG. The company integrated five of its 200W TEGs into a single 1,000 W diesel engine solution that directly converts exhaust waste heat into electrical energy to increase fuel efficiency and lower costs.

With this demonstration, GMZ has successfully reached the next milestone in the $1.5 million vehicle efficiency program sponsored by the US Army Tank Automotive Research, Development and Engineering Center (TARDEC) and administered by the U.S. Department of Energy (DOE).

Vanderbilt/ORNL team discovers new form of crystalline order that could be attractive for thermoelectric applications

November 17, 2014

A team of researchers from Vanderbilt University and Oak Ridge National Laboratory (ORNL) has discovered an entirely new form of crystalline order that simultaneously exhibits both crystal and polycrystalline properties, which they describe as “interlaced crystals.”

The interlaced crystal arrangement has properties that could make it ideal for thermoelectric applications. The discovery of materials with improved thermoelectric efficiency could increase the efficiency of electrical power generation, improve automobile mileage and reduce the cost of air conditioning. Writing in the journal Nature Communications, the researchers reported finding this unusual arrangement of atoms while studying nanoparticles made from the semiconductor copper-indium sulfide (CIS), which is being actively studied for use in solar cells.

October 21, 2014

Researchers at GMZ Energy, a provider of nano-structured thermoelectric generation (TEG) power solutions for mobile and stationary waste-heat recovery (earlier post), with their colleagues at the University of Houston and Bosch, have developed a new Hafnium-free p-type half-Heusler material which offers substantially lower raw material cost than conventional half-Heusler materials. The material also features enhanced performance and mechanical strength due to GMZ’s patented nanostructuring process.

As presented in a paper published in the RSC journal Energy & Environmental Science, the new material improves thermoelectric power output compared to a conventional Hafnium-based product. Further, by replacing the costly Hafnium element with GMZ’s proprietary formulation, the overall cost-per-watt of the TEG is lowered. Cost reduction is beneficial for vehicle and industrial waste heat recovery applications, the developers noted in their paper.

October 17, 2014

In May, researchers at MIT and Stanford University reported the development of new battery technology for the conversion of low-temperature waste heat into electricity in cases where temperature differences are less than 100 ˚Celsius. The thermally regenerative electrochemical cycle (TREC) uses the dependence of electrode potential on temperature to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying the temperature, an electrochemical cell is charged at a lower voltage than discharged; thus, thermal energy is converted to electricity. (Earlier post.)

Now, in a paper in the ACS journal Nano Letters, the team reports a refinement of the earlier Prussian blue analog-based system system, which although it operated with high efficiency, used an ion-selective membrane which, in turn, raised concerns about the overall cost. The refined system is a membrane-free battery with a nickel hexacyanoferrate (NiHCF) cathode and a silver/silver chloride anode. When the battery is discharged at 15 °C and recharged at 55 °C, thermal-to-electricity conversion efficiencies of 2.6% and 3.5% are achieved with assumed heat recuperation of 50% and 70%, respectively.

GMZ Energy announces new, high-power thermoelectric module: TG16-1.0

October 01, 2014

TG16. Click to enlarge.

GMZ Energy, a developer of high temperature thermoelectric generation (TEG) solutions, has introduced the TG16-1.0, a new thermoelectric module capable of producing twice the power of the company’s first product, the TG8-1.0. By doubling the power density, GMZ’s new module substantially increases performance while maintaining a minimal footprint.

GMZ has been using TG8 modules in developing vehicular thermoelectric generators for the Bradley Fighting Vehicle (1 kW TEG) as well as to design and to integrate a light-duty vehicle TEG into a Honda Accord as part of a DOE-funded project. (Earlier post.)

September 11, 2014

Renault Trucks’ heavy-duty Optifuel Lab 2 laboratory vehicle brings together various technologies designed to reduce fuel consumption in heavy-duty trucks and to prepare the way for future production models. Renault Trucks will display a scale model of Optifuel Lab 2 at the upcoming IAA. The vehicle is currently on the road to calculate the fuel savings it can achieve. These figures will be announced during the first quarter of 2015.

Optifuel Lab 2 has 20 technologies on board, each one of which addresses the four main issues associated with consumption: energy management, aerodynamics, wheel resistance and driving aids. Based on a Renault Trucks T, Optifuel Lab 2 is an ongoing version of the Optifuel Lab 1 introduced in 2009. The project has been developed with support from eight partners: Plastic Omnium, Michelin, Sunpower, Renault, IFP Energies Nouvelles, CEP-Armines, CETHIL-INSA from Lyon and LMFA-Ecole Centrale from Lyon. It is also supported by ADEMA, the French Agency for the Environment and Energy Control.

MIT/Stanford team develops battery technology for the conversion of low-grade waste heat to power; TREC

May 22, 2014

Researchers at MIT and Stanford University have developed new battery technology for the conversion of low-temperature waste heat into electricity in cases where temperature differences are less than 100 degrees Celsius. Their approach is based on a phenomenon called the thermogalvanic effect—the dependence of electrode potential on temperature—and is described in a paper published in the journal Nature Communications by postdoc Yuan Yang and professor Gang Chen at MIT, postdoc Seok Woo Lee and professor Yi Cui at Stanford, and three others.

The MIT and Stanford team devised an electrochemical system using a copper hexacyanoferrate cathode and a Cu/Cu2+ anode to convert heat into electricity. The thermally regenerative electrochemical cycle (TREC) entails a four-step process: (1) heating up the cell with waste heat; (2) charging at high temperature; (3) cooling down the cell; (4) discharging at low temperature.

Dearman-led consortium awarded $3.1M to develop waste-heat-recovery system using liquid air engine

April 23, 2014

A consortium led by the Dearman Engine Company has been awarded £1.86 million (US$3.12 million) in the latest round of IDP10 funding from the UK’s Technology Strategy Board to support the development of a heat-recovery system for urban commercial vehicles. The tenth competition under the Low Carbon Vehicles Innovation Platform’s integrated delivery program (IDP), IDP10 is targeting the building of an integrated low-carbon-vehicle innovation chain, from the science base, through collaborative R&D to fleet-level demonstration.

The Dearman project is to deliver a production-feasible waste-heat recovery system for urban commercial vehicles, which offers life-cycle CO2 savings of up to 40%; fuel savings of 25%, with the potential of up to almost 50%; and potential payback in less than three years. The project uses the Dearman Engine, a highly-efficient liquid nitrogen or air (LiN) engine (earlier post) that harvests low-grade heat sources and, in this configuration, is most effective in urban duty cycles, working with the internal combustion engine (ICE) as a hybrid powertrain.

April 07, 2014

A recently completed European project coordinated by Centro Ricerche Fiat (CRF) demonstrated the technical feasibility of a Bi2Te3-based thermoelectric generator (TEG) for waste heat recovery for application to a diesel light-duty truck (LDT). The project “Reduced energy consumption by massive thermoelectric waste heat recovery in light-duty trucks” (HeatReCar) focused on thermoelectrics to provide electricity, either to on-board components or to the power train of hybrid electric vehicles. Reduced fuel consumption for these purposes translates to emissions reductions.

TE materials have been employed previously in automotive applications but have not achieved reasonable conversion efficiencies. The researchers tackled this issue in two ways. They selected bismuth telluride (Bi2Te3) suitable for lower operating temperatures in a diesel engine. They also optimized the geometry of heat transfer surfaces to maximize the temperature difference available to the TE modules. The technology was implemented in a prototype TE generator (TEG) for a diesel IVECO Daily light-duty truck (LDT) in common use in the EU.